rate-limit-redis: PromiseRejectionHandledWarning: Promise rejection was handled asynchronously

Description

I get the following error the first time a request comes in:

(node:66707) PromiseRejectionHandledWarning: Promise rejection was handled asynchronously (rejection id: 4)
    at handledRejection (node:internal/process/promises:172:23)
    at promiseRejectHandler (node:internal/process/promises:118:7)
    at evalCommand (...)
    at RedisStore.runCommandWithRetry (...)
    at RedisStore.increment (...)
    at processTicksAndRejections (node:internal/process/task_queues:95:5)
    at async node_modules/express-rate-limit/dist/index.cjs:553:5

Possibly because of a missing await here: https://github.com/express-rate-limit/rate-limit-redis/blob/f9b187878a554a89495c349e43a31af17abcb731/source/lib.ts#L110C14-L110C14

Library version

^6.10.0

Node version

v18.12.1

Typescript version (if you are using it)

5.0.4

Module system

CommonJS

About this issue

Original URL
State: open
Created 10 months ago
Reactions: 1
Comments: 15 (9 by maintainers)

Most upvoted comments

Okay I’m sorry, I don’t think it’s possible today

That’s fine.

FYI, by making sure that the redis connection is established before constructing an instance RedisStore got rid of the warning. The lack of a connection during construction was the issue all along for me.

Thanks, this helped fix the odd 504s when the redis store was used to rate limit a cluster behind a load balancer.

Here’s a snippet for the reference:

import { promisify } from "util";
import { rateLimit } from "express-rate-limit";
import RedisStore from "rate-limit-redis";
// your client config, something like const redisClient = new RedisClient(...);
import { redisClient } from "../redis";

let store: RedisStore | undefined = undefined;

async function initializeRateLimitStore() {
  try {
    const ping = promisify(redisClient.ping).bind(redisClient);
    await ping();
    store = new RedisStore({
      // @ts-expect-error - Known issue: the `call` function is not present in @types/ioredis
      sendCommand: (...args: string[]) => redisClient.call(...args),
    });
  } catch (err) {
    // log and handle
  }
}

(async () => {
  await initializeRateLimitStore();
})();

const redisLimit = rateLimit({
  store,
  // rest of your init params ...
})

versions: rate-limit-redis@^4.0.0, express-rate-limit@^7.0.1

v11t on Sep 21, 2023

Great! I’ll work on a PR for the same.

Also, I think it should be possible to propagate an error back, any error thrown within the middleware should be passed to the error handler defined for express.

gamemaker1 on Sep 11, 2023

Okay I’m sorry, I don’t think it’s possible today

That’s fine.

FYI, by making sure that the redis connection is established before constructing an instance RedisStore got rid of the warning. The lack of a connection during construction was the issue all along for me.

abhijeetviswa on Sep 9, 2023